VMs available in >5 minutes after upgrading Debian. Why?

Sep 03, 2019

At work, we manage a fleet of bare metal servers and
virtual machines, running Debian GNU/Linux. Upgrades to a new major are often
very challenging; not because of the actual upgrade path, but because of the
unwanted side-effects that noone had predicted.

One of these side-effects was: “Why this shiny Buster VM takes 5 minutes to
boot?“. Together with my colleague
Alexandros Afentoulis, we figured out the issue,
fixed it and wrote a post about it. The real root cause is a number of changes
that happened to Debian GNU/Linux regarding entropy gathering (!).